C++ PendingScript类代码示例

void HTMLScriptRunner::executePendingScriptAndDispatchEvent(PendingScript& pendingScript, PendingScriptType pendingScriptType)
{
    bool errorOccurred = false;
    ScriptSourceCode sourceCode = sourceFromPendingScript(pendingScript, errorOccurred);

    // Stop watching loads before executeScript to prevent recursion if the script reloads itself.
    if (pendingScript.resource() && pendingScript.watchingForLoad())
        stopWatchingForLoad(pendingScript);

    if (!isExecutingScript()) {
        Microtask::performCheckpoint();
        if (pendingScriptType == PendingScriptBlockingParser) {
            m_hasScriptsWaitingForResources = !m_document->isScriptExecutionReady();
            // The parser cannot be unblocked as a microtask requested another resource
            if (m_hasScriptsWaitingForResources)
                return;
        }
    }

    // Clear the pending script before possible rentrancy from executeScript()
    RefPtr<Element> element = pendingScript.releaseElementAndClear();
    if (ScriptLoader* scriptLoader = toScriptLoaderIfPossible(element.get())) {
        NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel);
        IgnoreDestructiveWriteCountIncrementer ignoreDestructiveWriteCountIncrementer(m_document);
        if (errorOccurred)
            scriptLoader->dispatchErrorEvent();
        else {
            ASSERT(isExecutingScript());
            scriptLoader->executeScript(sourceCode);
            element->dispatchEvent(createScriptLoadEvent());
        }
    }
    ASSERT(!isExecutingScript());
}

void HTMLScriptRunner::executePendingScriptAndDispatchEvent(PendingScript& pendingScript)
{
    bool errorOccurred = false;
    ScriptSourceCode sourceCode = sourceFromPendingScript(pendingScript, errorOccurred);

    // Stop watching loads before executeScript to prevent recursion if the script reloads itself.
    if (pendingScript.cachedScript() && pendingScript.watchingForLoad())
        stopWatchingForLoad(pendingScript);

    if (!isExecutingScript()) {
#if ENABLE(CUSTOM_ELEMENTS)
        CustomElementRegistry::deliverAllLifecycleCallbacks();
#endif
        MutationObserver::deliverAllMutations();
    }

    // Clear the pending script before possible rentrancy from executeScript()
    RefPtr<Element> element = pendingScript.releaseElementAndClear();
    if (ScriptElement* scriptElement = toScriptElement(element.get())) {
        NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel);
        IgnoreDestructiveWriteCountIncrementer ignoreDestructiveWriteCountIncrementer(m_document);
        if (errorOccurred)
            scriptElement->dispatchErrorEvent();
        else {
            ASSERT(isExecutingScript());
            scriptElement->executeScript(sourceCode);
            element->dispatchEvent(createScriptLoadEvent());
        }
    }
    ASSERT(!isExecutingScript());
}

void HTMLScriptRunner::executePendingScriptAndDispatchEvent(PendingScript& pendingScript)
{
    bool errorOccurred = false;
    ScriptSourceCode sourceCode = sourceFromPendingScript(pendingScript, errorOccurred);

    // Stop watching loads before executeScript to prevent recursion if the script reloads itself.
    if (pendingScript.resource() && pendingScript.watchingForLoad())
        stopWatchingForLoad(pendingScript);

    if (!isExecutingScript())
        Microtask::performCheckpoint();

    // Clear the pending script before possible rentrancy from executeScript()
    RefPtr<Element> element = pendingScript.releaseElementAndClear();
    if (ScriptLoader* scriptLoader = toScriptLoaderIfPossible(element.get())) {
        NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel);
        IgnoreDestructiveWriteCountIncrementer ignoreDestructiveWriteCountIncrementer(m_document);
        if (errorOccurred)
            scriptLoader->dispatchErrorEvent();
        else {
            ASSERT(isExecutingScript());
            scriptLoader->executeScript(sourceCode);
            element->dispatchEvent(createScriptLoadEvent());
        }
    }
    ASSERT(!isExecutingScript());
}

void HTMLDocumentParser::watchForLoad(PendingScript& pendingScript)
{
    ASSERT(!pendingScript.isLoaded());
    // setClient would call notifyFinished if the load were complete.
    // Callers do not expect to be re-entered from this call, so they should
    // not an already-loaded PendingScript.
    pendingScript.setClient(this);
}

bool HTMLScriptRunner::isPendingScriptReady(const PendingScript& script)
{
    m_hasScriptsWaitingForResources = !m_document->haveStylesheetsAndImportsLoaded();
    if (m_hasScriptsWaitingForResources)
        return false;
    if (script.resource() && !script.resource()->isLoaded())
        return false;
    return true;
}

bool HTMLScriptRunner::isPendingScriptReady(const PendingScript& script)
{
    m_hasScriptsWaitingForStylesheets = !m_document->haveStylesheetsLoaded();
    if (m_hasScriptsWaitingForStylesheets)
        return false;
    if (script.cachedScript() && !script.cachedScript()->isLoaded())
        return false;
    return true;
}

void HTMLScriptRunner::requestDeferredScript(Element* element)
{
    PendingScript pendingScript;
    if (!requestPendingScript(pendingScript, element))
        return;

    ASSERT(pendingScript.cachedScript());
    m_scriptsToExecuteAfterParsing.append(pendingScript);
}

bool HTMLScriptRunner::isPendingScriptReady(const PendingScript& script)
{
    m_hasScriptsWaitingForResources = !m_document->isScriptExecutionReady();
    if (m_hasScriptsWaitingForResources)
        return false;
    if (script.resource() && !script.resource()->isLoaded())
        return false;
    return true;
}

void ScriptElement::executeScriptForScriptRunner(PendingScript& pendingScript)
{
    if (auto* loadableScript = pendingScript.loadableScript())
        executeScriptAndDispatchEvent(*loadableScript);
    else {
        ASSERT(!pendingScript.wasErrored());
        executeScript(ScriptSourceCode(scriptContent(), m_element.document().url(), pendingScript.startingPosition()));
        dispatchLoadEvent();
    }
}

ScriptSourceCode HTMLScriptRunner::sourceFromPendingScript(const PendingScript& script, bool& errorOccurred) const
{
    if (script.cachedScript()) {
        errorOccurred = script.cachedScript()->errorOccurred();
        ASSERT(script.cachedScript()->isLoaded());
        return ScriptSourceCode(script.cachedScript());
    }
    errorOccurred = false;
    return ScriptSourceCode(script.element()->textContent(), documentURLForScriptExecution(m_document), script.startingPosition());
}

void ScriptRunner::notifyFinished(PendingScript& pendingScript)
{
    if (pendingScript.element().willExecuteInOrder())
        ASSERT(!m_scriptsToExecuteInOrder.isEmpty());
    else {
        ASSERT(m_pendingAsyncScripts.contains(pendingScript));
        m_scriptsToExecuteSoon.append(m_pendingAsyncScripts.take(pendingScript)->ptr());
    }
    pendingScript.clearClient();
    m_timer.startOneShot(0);
}

HTMLScriptRunner::~HTMLScriptRunner()
{
    // FIXME: Should we be passed a "done loading/parsing" callback sooner than destruction?
    if (m_parsingBlockingScript.cachedScript() && m_parsingBlockingScript.watchingForLoad())
        stopWatchingForLoad(m_parsingBlockingScript);

    while (!m_scriptsToExecuteAfterParsing.isEmpty()) {
        PendingScript pendingScript = m_scriptsToExecuteAfterParsing.takeFirst();
        if (pendingScript.cachedScript() && pendingScript.watchingForLoad())
            stopWatchingForLoad(pendingScript);
    }
}

bool HTMLScriptRunner::requestPendingScript(PendingScript& pendingScript, Element* script) const
{
    ASSERT(!pendingScript.element());
    pendingScript.setElement(script);
    // This should correctly return 0 for empty or invalid srcValues.
    CachedScript* cachedScript = toScriptElement(script)->cachedScript().get();
    if (!cachedScript) {
        notImplemented(); // Dispatch error event.
        return false;
    }
    pendingScript.setCachedScript(cachedScript);
    return true;
}

bool HTMLScriptRunner::requestPendingScript(PendingScript& pendingScript, Element* script) const
{
    ASSERT(!pendingScript.element());
    pendingScript.setElement(script);
    // This should correctly return 0 for empty or invalid srcValues.
    ScriptResource* resource = toScriptLoaderIfPossible(script)->resource().get();
    if (!resource) {
        notImplemented(); // Dispatch error event.
        return false;
    }
    pendingScript.setScriptResource(resource);
    return true;
}

void HTMLScriptRunner::detach()
{
    if (!m_document)
        return;

    m_parserBlockingScript->stopWatchingForLoad();
    m_parserBlockingScript->releaseElementAndClear();

    while (!m_scriptsToExecuteAfterParsing.isEmpty()) {
        PendingScript* pendingScript = m_scriptsToExecuteAfterParsing.takeFirst();
        pendingScript->stopWatchingForLoad();
        pendingScript->releaseElementAndClear();
    }
    m_document = nullptr;
}